This C-DEBI Research Exchange was awarded for travel to the ECORD Summer School Course: Subduction Zone Processes hosted by MARUM in Bremen, Germany. This course offered many unique opportunities including networking with international scientists of various disciplines, learning shipboard operations, and improving grant writing abilities. This two-week course surveyed various types of subduction zone environments and included a wide variety of topics including geology, petrology, geochemistry, sedimentology, and microbiology. We participated in small group exercises that surveyed physical properties, core logging, rock geochemistry, downhole logging, core descriptions, thin sections, and temperature and heat flow. Each of these activities were mimicking onboard operations which allowed us to understand how sediment cores were processed on expeditions. This experience allowed me to make numerous contacts with future colleagues and collaborators while also receiving training for future expeditions. This course was relevant to C-DEBI Research Themes 2 (Activities, Communities, and Ecosystems) and 3 (Metabolism, Survival, and Adaptation) because we connected life with surrounding abiotic conditions including geochemistry, geology, petrology, and sedimentology.
Our understanding of phosphorus (P) dynamics in the deep subseafloor environment remains limited. Here we investigate potential microbial P uptake mechanisms in oligotrophic marine sediments beneath the North Atlantic Gyre and their effects on the relative distribution of organic P compounds as a function of burial depth and changing redox conditions. We use metagenomic analyses to determine the presence of microbial functional genes pertaining to P uptake and metabolism, and solution 31P nuclear magnetic resonance spectroscopy (31P NMR) to characterize and quantify P substrates. Phosphorus compounds or compound classes identified with 31P NMR include inorganic P compounds (orthophosphate, pyrophosphate, polyphosphate), phosphonates, orthophosphate monoesters (including inositol hexakisphosphate stereoisomers) and orthophosphate diesters (including DNA and phospholipid degradation products). Some of the genes identified include genes related to phosphate transport, phosphonate and polyphosphate metabolism, as well as phosphite uptake. Our findings suggest that the deep sedimentary biosphere may have adapted to take advantage of a wide array of P substrates and could play a role in the gradual breakdown of inositol and sugar phosphates, as well as reduced P compounds and polyphosphates.